1. Field of the Invention
The present invention relates to an energy damper-storage device and compensating mechanism for a vehicle access ramp, particularly a low floor vehicle access ramp, sometimes called a “flip-over” or “fold-out” ramp.
2. Description of Related Art
A flip-over ramp assembly is normally stowed in a generally horizontal position in a recess in a vehicle floor and can be pivoted upward and outward to a downward sloping deployed position after the vehicle door has been opened as shown, for example, in U.S. Pat. No. 6,179,545 entitled “Flip-Over Ramp.” The ramp assembly comprises a mounting enclosure and a ramp, which are pivotally connected at their adjacent edges, which provides a horizontal axis for movement of the ramp between deployed and stowed positions.
In the typical application, the ramp is located in the front door of the vehicle with a deployment path perpendicular to the length of the vehicle. In the fully stowed position, the ramp is essentially coplanar with the vehicle floor. In the deployed position, the ramp has moved through the front doorway to create a sloped surface between the sidewalk and the vehicle floor. The torque about the axis of rotation between the stowed and deployed positions is maximized when the ramp is at the extreme positions (fully deployed and fully stowed) and minimized when the ramp is positioned halfway between the extremes (i.e., when the ramp plate is at substantially right angles to the vehicle floor).
Ramp deploying mechanisms having torque compensating mechanisms are generally known in the art. See, for example, U.S. Pat. No. 6,843,635 entitled “Vehicle Fold-Out Ramp.” However, typical prior art devices are often very complex and difficult to install and maintain. Thus, the reliability of such devices is reduced. When such devices fail, substantial forces are needed to move the vehicle ramp between stowed and deployed positions, which requires excessive manual labor or very heavy bearing loads during power-assisted stowing and deploying. Thus, typical prior art devices impose undue labor and material expense burdens on users. Further, such devices fail to provide a dampener for preventing free fall of the ramp when the ramp is positioned between the fully deployed and fully stowed positions.
Accordingly, there is a general need for a deploying mechanism for a vehicle access ramp that effectively counterbalances the weight of the vehicle access ramp so as to reduce the force required to move the ramp between deployed and stowed positions, as well as a corresponding dampening mechanism for preventing free fall of the ramp that eases manual operation, is less complex, lower in cost, and easier to install and maintain in comparison to prior art devices.